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The behavior of neptunium in the ionic liquid betaine bistriflimide, [Hbet][Tf2N], has been studied spectroscopically at room temperature and 60 °C for the first time. An unprecedented complex redox chemistry is observed, with up to three oxidation states (IV, V and VI) and up to six Np species existing simultaneously. Both redox reactions and coordination of betaine are observed for Np(IV), (V) and (VI). Elevating the temperature accelerates the coordination of Np(v) with betaine and reduction reactions slow down. [ABSTRACT FROM AUTHOR]

Intra- and intermolecular force field parameters for the interaction of actinyl ions (AnO2n+, where, An = U, Np, Pu, Am and n = 1, 2) with water have been developed using quantum mechanical calculations. Water was modeled with the extended simple point charge potential (SPC/E). The resulting force field consists of a simple form in which intermolecular interactions are modeled with pairwise Lennard-Jones functions plus partial charge terms. Intramolecular bond stretching and angle bending are treated with harmonic functions. The new potentials were used to carry out extensive molecular dynamics simulations for each hydrated ion. Computed bond lengths, bond angles and coordination numbers agree well with known values and previous simulations. Hydration free energies, computed from molecular dynamics simulations as well as from quantum simulations with a solvation model, were in reasonable agreement with estimated experimental values. [ABSTRACT FROM AUTHOR]

Two americium(III) iodates, β-Am(IO3)3 (I) and α-Am(IO3)3 (II), have been prepared from the aqueous reactions of AmIII with KlO4 at 180 °C and have been characterized by single-crystal X-ray diffraction, diffuse reflectance, and Raman spectroscopy. The α-form is consistent with the known structure type I of anhydrous lanthanide iodates. It consists of a three-dimensional network of pyramidal iodate groups bridging [AmO8] polyhedra where each of the americium ions are coordinated to eight iodate ligands. The β-form reveals a novel architecture that is unknown within the f-element iodate series. β-Am(IO3)3 exhibits a two-dimensional layered structure with nine-coordinate AmIII atoms. Three crystallographically unique pyramidal iodate anions link the Am atoms into corrugated sheets that interact with one another through intermolecular IO3-⋯IO3- interactions forming dimeric I2O10 units. One of these anions utilizes all three O atoms to simultaneously bridge three Am atoms. The other two iodate ligands bridge only two Am atoms and have one terminal O atom. In contrast to α-Am(IO3)3, where the [IO3] ligands are solely corner-sharing with [AmO8] polyhedra, a complex arrangement of corner- and edge-sharing μ2- and μ3-[IO3] pyramids can be found in β-Am(IO3)3. Crystallographic data: I, monoclinic, space group P21/n, a = 8.871(3) Å, b = 5.933(2) Å, c = 15.315(4) Å, β = 96.948(4)°, V = 800.1(4) ų, Z= 4; II, monoclinic, space group P21/c, a = 7.243(2) Å, b = 8.538(3) Å, c = 13.513(5) Å, β = 100.123(6)°, V = 822.7(5) Å3, Z = 4. [ABSTRACT FROM AUTHOR]

The title compound was obtained by reacting UO2 powder in 2 M K2CO3 with hydrogen peroxide. The compound contains individual [U(CO3)2O2(O2)]4- ions, which are linked via an extended network of K atoms and hydrogen bonding. The U atom is coordinated to two trans-axial O atoms and six O atoms in the equatorial plane, forming distorted hexagonal bipyramids. The carbonate ligands are bound to the U center in a bidentate manner, with U-O bond distances ranging from 2.438 (5) to 2.488 (5) baring;. The perks group forms a threemembered ring with the U atom, with U-O bond distances of 2.256 (6) and 2.240 (6) baring;. The U=O bond distances of 1.806(5) and 1.817(5) baring;, and an O-U-O angle of 175.3 (3)° are characteristic of the linear uranyl(VI) unit. [ABSTRACT FROM AUTHOR]

A variety of imidazolium, quaternary ammonium, and phosphonium cation based ionic liquids were irradiated with γ-rays, 2-15 MeV protons and 5-20 MeV helium ions in order to examine their relative radiation stability and potential hazards for application in advanced nuclear fuel cycles. Molecular hydrogen production can be taken as an overall indicator of radiation stability, and was found to be considerably lower for the γ-irradiated aromatic imidazolium based compounds when compared to the other aliphatic based media. Increasing the length of the aliphatic side chain increases the H2 yields for all the compounds examined. Little difference is found in the production of H2 between the quaternary ammonium and phosphonium based ionic liquids with similar length side chains. Yields of H2 increase substantially from γ-rays to 5 MeV He ions for the imidazolium based ionic liquids, but little variation with radiation type is observed for the quaternary ammonium and phosphonium based ionic liquids. The imidazolium based ionic liquids show a darkening with increasing dose and the UV-Visible spectra show an increase in absorption from 240 to 400 nm that is probably due to induced changes in the cation. FTIR spectra show little variation with radiolysis, which is consistent with the low H2 yields. The formation of a new peak at 1658 cm-1 is attributable to the formation of acyclic disubstituted alkene bonds in the irradiated imidazolium based compounds. [ABSTRACT FROM AUTHOR]

Abstract: A new strategy for improving the robustness of membrane-based ion-selective electrodes (ISEs) is introduced based on the incorporation of microsphere-immobilized ionophores into plasticized polymer membranes. As a model system, a Cs+-selective electrode was developed by doping ethylene glycol-functionalized cross-linked polystyrene microspheres (P-EG) into a plasticized poly(vinyl chloride) (PVC) matrix containing sodium tetrakis-[3,5-bis(trifluoromethyl)phenyl] borate (TFPB) as the ion exchanger. Electrodes were evaluated with respect to Cs+ in terms of sensitivity, selectivity, and dynamic response. ISEs containing P-EG and TFPB that were plasticized with 2-nitrophenyl octyl ether (NPOE) yielded a linear range from 10−1 to 10−5 M Cs+, a slope of 55.4mV/decade, and a lower detection limit (log a Cs) of −5.3. In addition, these membranes also demonstrated superior selectivity over Li+, Na+, and alkaline earth metal ion interferents when compared to analogous membranes plasticized with bis(2-ethylhexyl) sebacate (DOS) or membranes containing a lipophilic, mobile ethylene glycol derivative (ethylene glycol monooctadecyl ether (U-EG)) as ionophore. [Copyright &y& Elsevier]